title: Ectopic expression of WUS in hypocotyl promotes cell division via GRP23 in Arabidopsis.
abstract: WUSCHEL (WUS) is essential for preventing stem cell differentiation in Arabidopsis. Here we report that in addition to its functions in meristematic stem cell maintenance, WUS is involved in the regulation of cell division. The WUS gain-of-function mutant, stem ectopic flowers (sef), displayed elongated hypocotyls, whereas the loss-of-function wus-1 mutant had shortened hypocotyls. The long hypocotyl in sef was due to the presence of more cells, rather than increased cell elongation. Microscopic observation, flow cytometry assays, quantitative RT-PCR (qRT-PCR), and histochemical staining of CycB1;1::GUS supported the hypothesis that ectopic cell division occurred in the sef hypocotyls after germination. Both immunoblot and qRT-PCR results showed that WUS was ectopically expressed in sef hypocotyls. Luciferase activity, chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assay (EMSA) showed that GLUTAMINE-RICH PROTEIN 23 (GRP23) expression can be activated by WUS and that GRP23 is a direct target gene of WUS. The phenotypes of 35S::GRP23 plants and GRP23 knockdown lines supported the notion that GRP23 mediates the effects of WUS on hypocotyl length. Together, our data suggest that ectopic expression of WUS in hypocotyl controls cell division through its target gene GRP23.
authors.affiliation: Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China ; University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Dajian
authors.initials: D
authors.lastname: Zhang
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Wang
authors.forename: Min
authors.initials: M
authors.lastname: Wang
authors.forename: Junhua
authors.initials: J
authors.lastname: Li
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Guo
authors.forename: Kang
authors.initials: K
authors.lastname: Chong
authors.forename: Yunyuan
authors.initials: Y
authors.lastname: Xu
mesh_terms: D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics*; D002455:Cell Division / Q000235:genetics*; D002843:Chromatin / Q000235:genetics; D035264:Flowers / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics*; D018546:Hypocotyl / Q000235:genetics*; D018519:Meristem / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D013234:Stem Cells / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D029681:Arabidopsis Proteins; D002843:Chromatin; C511742:GRP23 protein, Arabidopsis; D018398:Homeodomain Proteins; C518921:SEF protein, Arabidopsis; D014157:Transcription Factors; C116421:WUSCHEL protein, Arabidopsis